Title

Investigation of Environmental Effects on Phytoplankton Fluorescence Signatures on a Fluorescence Imaging Photometer

Date of Award

Fall 2018

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Michael L. Myrick,

Abstract

Phytoplankton play a vital role as primary producers in aquatic ecosystems and there is interest among the field in characterizing community structure in aquatic systems. One common approach to classifying phytoplankton is fluorescence excitation spectroscopy, which leverages the variation in types and concentrations of pigments among different phytoplankton taxonomic groups. Our group has developed an instrument the Fluorescence Imaging Photometer (FIP), which uses band-pass filters to classify single phytoplankton cells optically through fluorescence excitation ratios. A majority of our previous work focused on phytoplankton cultures grown in the lab under standard environmental conditions (nutrient availability, illumination levels, temperature, etc.). However, future projects lie in the field where these environmental conditions are variable. Other studies have shown response in pigment concentrations to environmental stimuli in a variety of phytoplankton species. This is of interest to us because varying pigment ratios could lead to “confusion” in classification of phytoplankton cells when measured on the FIP, especially in those pigments attached to the photosystem. However, most of the work in the literature is on bulk fluorescence signatures rather than single-cell fluorescence excitation ratios and none focus on the dynamics of response. This work set out to investigate the effect and dynamics of environmental conditions on fluorescence signatures of several phytoplankton species and their impact on our classification. More specifically, controlled experiments altering nitrogen availability and incident growth illumination were performed. We also investigate if cells do show a measurable change in fluorescence excitation ratios, can they “recover” when returned to standard conditions.

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